Automatic reclosing circuit-breaker system



Jul 5 1927.

y o. c. TRAVER AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Dec. 50. 1926 Aim v w 0, t H mc A J w 0 UJ b trip open the Patented July I 5, 1927.

UNITED STATES 1,635,061 PATENT OFFICE.

OLIVER C. TRAVER, OF SCHENEGTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC RECLOSING CIRCUIT-BREAKER SYSTEM.

Application filed December 30, 1926. Serial No. 158,090-' My invention relates to automatic reclosing circuit breakersystems, and particularly to a system in which the circuit breaker is automatically reclosed after it has been open a certain length of time. I

When a circuit breaker is opened by an overload, the length of time that it is (le sirable to maintain the circuit breaker open before it is reclosed depends upon the severity of theoverload that caused the circuit breaker to open. If the overload is not very severe, it is desirable to reclose the circuit breaker very soon after it opens, whereas ifthe overload is a very severe short circuit,

it is very desirable to have a much longer time elapse between the opening and the reclosing of the circuit breaker.

One object-of my invention is to provide an arrangement whereby the length of time that elapses between the opening and the reclosin of a circuit breaker depends upon the magnitude of a predetermined characteristic of the power that is flowing through the circuit breaker when it opens. In accordance with the preferred arrangement of my invention, the length of time is proportional to' the magnitude of the current flowing through the circuit breaker at the time it opens. I

My invention will be better understood from the following description, taken in connection with the accompanying drawing, which shows diagrammatically an automatic reclosing circuit breaker system embodying my invention, and its scope will be intedout in the appended claims.'

Referring to the accompanying drawing, 1 represents a circuit breaker, of any suitable type, which is arranged to connect together .two electric circuits 2 and 3. As shown, the circuit breaker 1 is provided with a closing coil 4, a latch 5 for holding the circuit lbreaker in its closed position, and a trip coil 6 which, when energized, trips the latch 5 so as to permit the circuit breaker to open. The circuit of the trip coil 6 is controlled by an overload relay which is arranged in any suitable manner so that it completes the circuit of the trip'c'oil 6 to circuit breaker 1 when the current fiowin through the circuit breaker exceeds a pre etermined value. As shown in the drawing, the overload relay 7 is energized by means of a current transformer 8 in the circuit 2.

The circuit of the closing coil 4 is controlled by a hesitating control relay'9, the circuit of which is controlled by a timing device 10 which is arranged to complete the circuit of the hesitating control relay 8 after the circuit breaker has been open a time interval which depends upon the amount of current flowing through the circuit breaker when the circuit breaker opens.

As shown in the drawing, the timing device 10 comprises a contact controlling member 11, shown as a disc, and a current responsive device 12, arranged to move the disc in a counterclockwise direction against the force exerted by a biasing spring 13. The current responsive device 12, which is shown as a shaded pole motor element, is energized from the current transformer 8 so that the torque exerted by the motor 12 varies with the current flowing through the circuit breaker 1. Therefore, the arrangement is such that the position of the disc at the instant the circuit breaker opens varies with the amount of current flowing through the circuit breaker at that instant. The disc is arranged so that it is free, except for the torque exerted by the spring 13, to move in a counterclockwise direction. Therefore, when an overload occurs, the disc moves substantially instantaneously to a position corresponding to the. severity of the overload. It will be observed that this portion of the device 10 is similar to an ordinary ammeter element. If desired, suitable drag magnets, not shown, may be added to the disc for stability. Preferably, the device is so arranged that the torque exerted, by the motor element 12 under normal load conditions is not suflicient to move the disc from its contact controlling position, in which position contacts 15 and 16 in the circuit of the hesitating control relay 7 are maintained in engagement by a pin 17 on the disc 11.

In order that the movement of the disc 11 from the position it occupies at the instant the circuit breaker opens to its contact controlling position'may be retarded so as to obtain the desired'time interval between the opening and the closing of thev circuit breaker, a retarding device 19, which ma be of an suitable type, examples of whic are well nown in the art, is provided. As shown, this retarding device 1s of the well known magnetic drag type, comprising a magnetic disc 20 rotating between the poles of suitable magnets 21. The disc 20 is arranged in any suitable manner, so that it is rotated by the disc 11 and therefore retards the movement of the disc 11 only when the disc 11 moves in a clockwise direction. This result is obtained in the arrangement shown in the drawing by the ratchet arrangement 22, which is a well known construction.

In order to prevent the circuit breaker from being reclosed in case the overload exceeds a predetermined value, the disc 11 is provided with a tooth 24 which is arranged to be moved far enough to be engaged by a pawl 25 when the current exceeds a predetermined value. The pawl 25, when in engagement with the tooth 24 maintains the disc in its lock out position until the pawl is released manually.

27 is a notching relay, which is arranged to be actuated each time the circuit breaker opens. As shown, the relay is of the type well known in the art. which arranger to open its contacts 28 in the circuit of the hesitating control relay 9 after the circuit breaker has been opened a predetermined number of times with less than a predetermined interval between each reclosure and the subsequent opening of the circuit breaker.

The operation of the arrangement shown is as follows: Under normal load conditions, the circuit breaker l is held closed by the latch 5. Vihen an overload occurs, overload relay 7 picks up and completes the circuit of the trip coil 6, so that the circuit breaker opens. The overload also causes the disc 11 to move a distance from its contact controlling position, which depends upon the amount of current flowing through the circuit breaker when it opens. The disc 11 takes its position substantially instantaneously on the occurrence of the overload because of the ratchet arrangement 22, which permits the disc 11 to move in a counter clockwise direction independently of the disc 20. I

The closing of the auxiliary contacts 29 on the circuit breaker when it opens completes the circuit of the coil 30 of the notch ing relay 27 through the contacts 28 of the notching relay. The relay 27 notches up one notch, but does not open its contacts 28 at this time.

As soon as the circuit breaker 1 opens, the motor element 12 of the timing device 10 becomes deenergized so that the spring 13 starts to move the disc 11 in a clockwise direction to its contact controlling position. The movement of the disc 11, however, is now retarded by the retarding means 19, since the direction of the disc 11 is such as to cause the ratchet arrangement 22 to engage.

After a predetermined time, which depends upon the distance the disc 11 has to move before it reaches its contact controlling position, the pin 17 on the disc 11 causes the contacts 15 and 16 to be moved into engagement, thereby completing the circuit of the hesitating control relay 9 through auxiliary contacts 29 on the circuit breaker and contacts 28 of the notching relay. The hesitating relay 9, in turn, completes the circuit of the closing coil 4 to close the circuit breaker 1.

In case the overload is still connected to the circuit when the circuit breaker is reclosed, the circuit breaker opens again and the above cycle of operation is repeated. Each time the breaker opens, the notching relay 27 notches up another notch, until finally after the breaker has opened a predetermined number of times, it opens its contacts 28, thereby rendering the reclosing equipment inoperative until these contacts are reset manually.

In case the overload is severe-enough to cause the disc 11 to move to its lockout position, the pawl 25 engages the tooth 2l so that the breaker is prevented from being reclosed.

It will be observed that by means of my invention the time between the opening of the breaker and its reclosure is graded continuously for all values of over-current up to a predetermined value, abovewhich the breaker is not reclosed at all.

lVhile I have, in accordance with the patent statues, shown and described my invention as applied to a particular arrangement and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aim in the appended claims to cover all such changes and modilications as fall within the true spirit and scope of my invention.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, means for effecting the opening of said circuit breaker, and means for effecting the reclosing of said circuit breaker after a time which depends upon the magnitude of a predetermined characteristic of the electric power being transmitted through the circuit breaker at the time it opens.

2. In an automatic recloslng circuit breaker system, a circuit breaker for connecting two electric circuits together, means for effecting the opening of said circuit breaker, and timing means arranged to ef feet the reclosing of said circuit breaker after a time which depends upon the amount of current flowing through said circuit breaker at the time it opens.

3. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means for efiecting the openmg of said circuit breaker, and a timing device for controlling the reclosing of said cir-' cuit breaker comprising overload responsive means for varying the time of operation of said timing device.

4. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means for effecting the opening of said circuit breaker, and a timing device for controlling the reclosing of said circuit breaker comprising a contact controlling member, current responsive meansfor actuating said member in one direction, means for actuatin said member in the opposite direction, an means for retarding the movement of said'member in said last mentioned direction. N

5. In an automatic reclosing circuit breaker system, a circuitbreaker for connecting two electric circuits together, overload responsive means for eifecting the opening of said circuit breaker, and a timing device for controlling the reclosing of said circuit breaker comprising a contact controlling member normally biased to contact controlling position, current responsive means arranged tovary the position of said member in accordance with the amount of current through said circuit breaker, and means for retarding the movement of said members to contact controlling position after the opening of said circuit breaker.

6. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means'for effecting the open-" ing of said circuit breaker, and a timing device for controlling the reclosing of said circuit breaker comprising a contact controllin member normally biased to contact controIling position, current responsive means arranged to vary the osition of said mem her in accordance wit the amount of cur rent through said circuit breaker when closed, means for retarding the movement of said member to contact controlling position after the opening of said circuit breaker, and means for preventing the movement of said member to contact controlling position after the opening of said circuit breaker when said current responsive means causes said member to be moved to a predetermined position.

7. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means for efiecting the opening of said circuit breakeryand a timing device for controlling the reclosing of said circuit breaker comprising a contact controlling member, current responsive means for actuating said member in one direction,

and means for retarding the movement of said member only in the opposite direction.

8. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means for effecting the opening of said circuit breaker, and means arranged to effect'the reclosing of said circuit breaker after a time which is proportional to the amount of current flowing through said circuit breaker at the time it opens.

9. In an automatic reclosing circuit breaker system, a circuit breaker for connecting two electric circuits together, overload responsive means for effecting the opening of said circuit breaker, means arranged to eifect the reclosing of said circuit breaker after a time which is proportional to the amount of current flowing through said circuit breaker at the time it opens and for preventing the reclosing of said circuit breaker if the current is above a predetermined value when the circuit breaker opens. I p

In witness whereof, I have hereunto set my hand this 29th day of December, 1926.

OLIVER C. TRAVER. 

